1. Field of the Invention
The present invention relates to a fine worked product appearance inspection method. More specifically, the present invention relates to a worked product appearance inspection method and a worked product appearance inspection system suitable for the inspection, discrimination, and the like of an appearance of a worked product such as a lead frame for a semiconductor package or a spring member for a hard disk drive (a magnetic disk device) (particularly, a spring member for a suspension having a wiring).
2. Description of Related Art
It is desired to mass-produce fine worked products represented by lead frames for semiconductor packages and spring members for hard disk drives at low apparatus cost while maintaining high quality.
Among these fine worked products, the lead frame for a semiconductor package is, for example, employed as an internal wiring of a semiconductor package. As the high integration of the semiconductor package has recently progressed, a wiring pattern has been increasingly complicated.
The spring member for a hard disk drive (i.e., wiring-added suspension spring member) is employed to be incorporated into a magnetic head suspension which supports a magnetic head that writes and/or reads data to and from a disk. As a hard disk drive has been recently made smaller and thinner in size, the spring member is increasingly made smaller in size. Namely, the magnetic head suspension into which the spring member is incorporated applies a pressing load to a slider that mounts thereon the magnetic head. The distance between disks is narrowed as the hard disk drive is made smaller and thinner. Accordingly, the slider and the magnetic head suspension are made smaller and thinner. Thereby, the spring member for a hard disk drive has been made smaller.
As stated above, when producing the fine worked products such as the lead frame for a semiconductor package or the spring member for a hard disk drive or the like, the individual worked product is increasingly made finer and smaller in size. Further, as the mass-production of the semiconductor packages and the hard disk drives progress, fine worked products employed therefor have been required in large quantities.
Due to this, to manufacture these fine worked products, a method of manufacturing the worked products by etching has been used.
Specifically, when the lead frame for a semiconductor package is manufactured, for example, resist is coated on both sides of a sheet-like workpiece material and the resultant workpiece material is subjected to plate-making and etching, thereby manufacturing a product holding sheet that holds a plurality of lead frames as fine worked products. The product holding sheet is constituted to integrally hold parts of outer peripheries of the plurality of worked products by a frame portion through supporting members, in the view of mass productivity and efficiency. Typically, a predetermined number of worked products are integrated into one frame and a plurality of frames thus integrated are “multiply patterned” on the entire product holding sheet. When producing such a product holding sheet, after the plate-making and the etching, the resist is peeled off from the workpiece material and the workpiece material is washed. The final product holding sheet thus obtained is cut at predetermined positions at need to provide inspection target sheets each having a predetermined size. Appearance of the worked products are inspected per inspection target sheet.
Meanwhile, when the spring member for a hard disk drive is manufactured, a sheet-like workpiece material is subjected to complicated working including a photo-etching step and a plating step, thereby manufacturing a product holding sheet that holds a plurality of spring members as fine worked products. Similarly to the product holding sheet for the lead frames, the product holding sheet thus manufactured is constituted so that a predetermined number of worked products are integrated into one frame and a plurality of frames thus integrated are “multiply patterned” on the entire product holding sheet. Similarly to the product holding sheet for the lead frames, the product holding sheet thus obtained is cut at predetermined positions at need to provide inspection target sheets each having a predetermined size. Appearance of the worked products are inspected per inspection target sheet.
To inspect such worked products, the following inspection method has been conventionally conducted. A series of operations including a plurality of processing necessary for an inspection (e.g., a processing for imaging each worked product and fetching image data, a processing for comparing each fetched image data with basic image data prepared in advance and thereby extracting a defect candidate part under predetermined setting conditions, and a processing for displaying an enlarged image of the extracted defect candidate part and determining whether or not the defect candidate part is really a defect part) are performed per inspection target sheet by one inspection system.
However, when the fine worked products represented by the lead frame for a semiconductor package or the spring member for a hard disk drive are manufactured, the worked products in one inspection target sheet to be inspected are quite large in number and an inspection accuracy requirement is quite strict. Therefore, it disadvantageously takes lots of time to perform the processings necessary for the inspection. In performing the processing for fetching the image data of each worked product, in particular, it is necessary to image the worked product and fetch the image data using an area sensor such as a CCD or the like per inspection target sheet several tens of times. Further, the processing for determining whether or not the defect candidate part really is a defect part requires quite labor. As a result, it takes considerable time to perform the entire processings mainly due to these processings.
To solve these disadvantages, it is possible to simply increase the number of inspection systems that perform the processings necessary for the inspection. When so, however, it is impossible to attain an effect of reducing labor and time proportional to an increase in apparatus cost. As a result, demand for mass productivity and quality improvement cannot be satisfied.
As such a worked product inspection, various inspections such as a visual inspection, an inspection using a loupe, and an inspection using a stereoscope, other than the inspection using the above described inspection apparatus, are performed inside manufactures that manufacture worked products or outside the manufactures (that is, outsourcing). In these circumstances, the apparatus cost, time, and the like for the inspection using the above described inspection apparatus are restricted.